It's indeed a relatively recent addition, but the idea that the king would get a special move is a bit older [0]. [0] https://en.wikipedia.org/wiki/Castling#Hi

It's indeed a relatively recent addition, but the idea that the king would get a special move is a bit older [0]. [0] https://en.wikipedia.org/wiki/Castling#History https://en.wikipedia.org/wiki/Castling#History